1. Field of the Invention
The present invention relates to a jaw crusher which moves a jaw near to and away from the other jaw to crush raw materials and a self-propelled crushing machine having the same.
2. Description of Related Art
There is a known conventional jaw crusher which moves a swing jaw near to and away from a fixed jaw to crush raw materials (for example, refer to published Japanese Patent No. 3133766, pages 5 to 8, FIGS. 1 and 2).
In this jaw crusher, the lower side of the swing jaw is supported by a reaction force receiver mechanism including a toggle plate and a toggle block. A most widely used type of reaction force receiver mechanism is a down-thrust type in which the toggle plate contacts the back of the swing jaw obliquely from upside toward downside. According to this down-thrust type, the swing jaw swings upward from downside when the swing jaw moves near to the fixed jaw.
If a reaction force receiver mechanism having a toggle plate is used, the toggle plate is merely clamped between the toggle block and the swing jaw. This kind of jaw crusher therefore is provided with a toggle plate holder mechanism, which prevents release of the swing jaw from its engagement with the toggle plate while the swing jaw is swinging. The toggle plate holder mechanism has a tension rod whose one end is set on the swing jaw. The tension rod is positioned along the toggle plate. The other end of the tension rod is biased by a tension spring. The biasing force of the tension spring biases the swing jaw to the toggle block side, to clamp the toggle plate.
In the reaction force receiver mechanism of the down-thrust type, the swing jaw moves upward from downside near to the fixed jaw, pressing the fixed jaw. At this time, however, the angle at which the swing jaw moves near to the fixed jaw is so small that raw materials slip on the fixed jaw. This results in a problem that the fixed jaw is worn out in a short time. Hence, another reaction force receiver mechanism of a so-called up-thrust type is known, in which the swing jaw moves near to the fixed jaw when the swing jaw swings downward from upside. In a jaw crusher having this reaction force receiver mechanism, the angle at which the swing jaw moves near to the fixed jaw is so large that raw materials hardly slip between the jaws. Accordingly, the lifetime of the jaws can be extended.
However, in this up-thrust type, the toggle plate contacts the swing jaw obliquely upward from downside due to the structure of the reaction force receiver mechanism. Therefore, if the tension rod and tension spring are positioned along the toggle plate in the above-described manner, ends of the rod and spring protrude into a discharge space below the jaw crusher. This results in a problem that the ends of the tension rod and tension spring interfere with crushed materials being discharged by a discharge conveyer or the like.
In order to prevent the end of the tension rod from protruding in the discharge space, the overall height of the jaw crusher has to be increased. However, in the case that the jaw crusher is mounted on the self-propelled crushing machine, the height thereof can not be increased unlimitedly due to a height limit for transportation purpose.